As conventional navigation apparatuses, there are widely known small-sized portable navigation apparatuses with a simplified structure and portability (hereinafter, referred to as Portable Navi), also known as Personal Navigation Device; and in-vehicle navigation apparatuses accommodated and fixed in a recess portion (DIN opening) formed in a dashboard of a vehicle. The in-vehicle navigation apparatuses are capable of guiding with high accuracy by use of the information supplied from vehicles such as vehicle speeds, and some of the in-vehicle navigation apparatuses are equipped with audio devices.
In recent years, the navigation apparatuses with portability of the Portable Navi and high-accuracy guide function of the in-vehicle navigation apparatus have been studied.
Patent Documents 1 and 2 disclose a configuration where a CD unit can be detached from an in-vehicle apparatus. Patent Documents 3 and 4 disclose a configuration where a navigation portion can be detached from an in-vehicle apparatus mounted in a vehicle. By removing the navigation portion from the in-vehicle apparatus, the navigation portion can be used as a Portable Navi of a single unit. Also, as disclosed in patent Document 5, the navigation apparatus is taken out of the vehicle and can be used while walking. In addition, when mounted in a vehicle, the navigation apparatus is in a car-navigation mode, and when taken out of the vehicle, the navigation apparatus is in a person-navigation mode.
In the attachment of the navigation portion into the in-vehicle apparatus, for example, the navigation portion is inserted and fitted into a recess portion provided at a front face of the in-vehicle apparatus.    Patent Document 1: Japanese Patent Application Publication No. 8-318792    Patent Document 2: Japanese Patent Application Publication No. 2002-328026    Patent Document 3: Japanese Patent Application Publication No. 2005-524570    Patent Document 4: Japanese Patent Application Publication No. 2001-239895    Patent Document 5: Japanese Patent Application Publication No. 2003-166848